I argue that cognitively mature human beings have an important sort of control or discretion over their own beliefs, but that to make good sense of this control, we must reject the common idea that it consists in a capacity to act on our belief-state by forming new beliefs or modifying ones we already hold. I propose that we exercise agential control over our beliefs, not primarily in doing things to alter our belief-state, but in holding whatever beliefs we hold. Our beliefs are thus not normally things on which we act; they are themselves our acts, in a sense I seek to explicate.